TL;dr: simply remove backport-iwlwifi-dkms on your Eoan system with Intel AC 9260 installed.
First, "the entire system will freeze" is to be resolved in bug 1855825, which will fix backport-iwlwifi-dkms in Eoan/Focal for generic Ubuntu, and Bionic for OEM projects. Eventually generic Bionic will have the fix in bug 1856024.
Second, the association failure problem when backport-iwlwifi-dkms is installed is currently a known issue in my list. Probably there is already a bug for it, takes some time to filter they out. TBD.
At last, this (1855637/1855825) issue is caused by a mainline patch backported to stable kernels, which modifies data structure layout, and while DKMS packages may carry a copy of kernel headers that it uses, such different data layout may cause unexpected behaviors, and in this case, it hangs your system. Ubuntu kernels will merge stable patches, so all Ubuntu kernels with this patch included are affected. So it follows, if you're running a slightly older kernel, it will be fine; if you don't use backport-iwlwifi-dkms, it will be fine, too.
DKMS is created to include features/fixes that are not currently in generic kernel "at the time". So it's not always "newer" than generic kernel.
@Wayne,
TL;dr: simply remove backport- iwlwifi- dkms on your Eoan system with Intel AC 9260 installed.
First, "the entire system will freeze" is to be resolved in bug 1855825, which will fix backport- iwlwifi- dkms in Eoan/Focal for generic Ubuntu, and Bionic for OEM projects. Eventually generic Bionic will have the fix in bug 1856024.
Second, the association failure problem when backport- iwlwifi- dkms is installed is currently a known issue in my list. Probably there is already a bug for it, takes some time to filter they out. TBD.
At last, this (1855637/1855825) issue is caused by a mainline patch backported to stable kernels, which modifies data structure layout, and while DKMS packages may carry a copy of kernel headers that it uses, such different data layout may cause unexpected behaviors, and in this case, it hangs your system. Ubuntu kernels will merge stable patches, so all Ubuntu kernels with this patch included are affected. So it follows, if you're running a slightly older kernel, it will be fine; if you don't use backport- iwlwifi- dkms, it will be fine, too.
DKMS is created to include features/fixes that are not currently in generic kernel "at the time". So it's not always "newer" than generic kernel.